As one of manufacturing processes of semiconductor devices, there is a CVD film forming process that is performed on a semiconductor wafer serving as a target substrate. In this process, the semiconductor wafer serving as a target substrate is heated to a specific temperature generally by using a heater plate (stage heater) also serving as a substrate mounting table. A general heater plate is disclosed in Japanese Patent Application Publication No. H10-326788.
It is ideal that a film is deposited only on the semiconductor wafer in the CVD film forming process. However, actually, a film is deposited on the heater plate which heats the semiconductor wafer, as well. That is because the heater plate has a deposition temperature or more. The film deposited on the heater plate is influenced by the rise and fall of the temperature of the chamber or the heater and repeatedly thermally expanded and contracted. Accordingly, a thermal stress is accumulated in the deposited film. Ultimately, the film is peeled off to generate particles. The generation of particles in the chamber may cause deterioration in production yield of the semiconductor devices.